Auto dimming vehicle mirror

ABSTRACT

A vehicle mirror assembly comprising a reflective element for reflecting incident light, the reflective element having a viewable side, a dimming element for varying the intensity of light reflected from the viewable side, a photo-electric power cell for powering the dimming element for varying the intensity of reflected light and a controller for controlling the dimming element in response to ambient light conditions, wherein, in use, the intensity of the light reflected from the viewable side is reduced in low ambient light conditions. In other embodiments a power source is defined, for providing interment power to power the dimming element for varying the intensity of light reflected, the power being supplied by the photo-electric power cell.

FIELD OF THE INVENTION

The present invention relates to vehicle mirrors and in particular tovehicle mirrors that have the capacity to decrease the intensity orreflected light (“dim”) during certain conditions.

BACKGROUND

Modern vehicles are equipped with a plurality (typically three) of rearview mirrors which, in use, are all positioned to allow the driver toview other vehicles behind his or her vehicle.

During night time driving conditions, glare caused by the reflection ofthe following vehicle head lights in these rear view mirrors presents aproblem to the driver. There is a need to reduce this glare whileallowing the driver to continue to see behind the vehicle.

Known solutions to night time head light glare have included interiorrear view mirrors that are manually manipulable between a day timereflecting positions and a night time reflecting position. These mirrorsuse first and second surface reflections from prisms with a reflectivecoating on one surface. Also known are external vehicle mirrors (wingmirrors) that have dimmable mirrors controlled and powered from thevehicle.

A disadvantage with known electronic dimming methods has been cost andcomplexity and the need to integrate with vehicle systems or othermirrors for a dimming signal and for power supply. Therefore, it isdesirable to develop an automatic dimming rear view mirror that detectslight from predetermined angles as a dimming signal or power supply.

It is an object of the invention to provide improved automatic dimmingfor ear view mirrors.

SUMMARY OF THE INVENTION

According to the invention there is provided a vehicle mirror assemblycomprising:

a reflective element for reflecting incident light, the reflectiveelement having a viewable side of the reflective element;

a means for varying the intensity of light reflected from the viewableside, such as a dimming element;

a photo-electrical power cell for powering the means for varying theintensity of reflected light or a dimming element in response to ambientlight conditions,

wherein, in use, the intensity of the light reflected from the viewableside is reduced in low ambient light conditions.

The reflection of incident light from the headlights of followingvehicles (glare light) at night is thereby reduced.

The means for varying the intensity of light reflected takes a number offorms. For instance it takes the form of a conventional reflectiveelement (a glass or plastic sheet having a thin reflective layer bondedto one side) overlayed with a light transmitting sheet that is dimmable.Or if may take the form of a special reflective element the reflectiveproperties of which are variable.

According to a first preferable form of the invention, the device forconverting light into electrical power uses the incident light toproduce sufficient real-time power to power the means for varying theintensity of light reflected without the need for a power storage means.

With this first preferable form of the invention, the source of power isglare light from following vehicles (for instance).

Preferably, the mirror assembly further comprises an incident lightdirectional element arranged and constructed to exclude incident lightfrom reaching the photo-electrical power cell where the angle ofincidence of the incident light falls outside of preset angles.

According to a second preferable form of the invention, mirror assemblyfurther comprises a power storage means wherein the source of power forthe means for varying the intensity of light reflected is ambient lightand the power storage means provides peak power to power the means forvarying the intensity of light reflected.

Preferably, the control means or controller for controlling the meansfor varying the intensity of reflected light comprises an ambient lightdirectional element and a photo-electrical switching device, the ambientlight directional element arranged and constructed to pass the ambientlight to the photo-electrical switching device only where the angle ofincidence of the ambient light falls within a preset range.

In an alternate embodiment, a transparent photo-electrical power cell isused, the power cell overlaying the means for varying the intensity oflight.

Specific embodiments of the invention will now be described in somefurther detail with reference to and as illustrated in the accompanyingfigures. These embodiments are illustrative, and are not meant to berestrictive of the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of a preferred embodiment of avehicle mirror assembly in accordance with the present invention;

FIG. 1 a is a schematic sectional view of an alternate embodiment of avehicle mirror assembly in accordance with the present invention;

FIG. 1 b is a schematic sectional view of an alternate embodiment of avehicle mirror assembly in accordance with the present invention;

FIG. 2 is a schematic sectional view of an alternate embodiment of avehicle mirror assembly in accordance with the present invention;

FIG. 3 is a schematic sectional view of an alternate embodiment of avehicle mirror assembly in accordance with the present invention;

FIG. 4 is a schematic view of a preferred embodiment of a vehicle mirrorassembly in accordance with the present invention;

FIG. 5 is a front plan view of the vehicle mirror assembly where thelight receiving aperture or lens is not behind the reflective element;

FIG. 6 is a front plan view of an alternate embodiment of the vehiclemirror assembly where the light receiving aperture or lens is not behindthe reflective element;

FIG. 7 is a front plan view of an alternate embodiment of the vehiclemirror assembly where the light receiving aperture or lens is not behindthe reflective element;

FIG. 8 is a schematic view of an alternate embodiment of the lightreceiving components of the vehicle mirror assembly;

FIG. 9 is a schematic view of an alternate embodiment of the lightreceiving components of the vehicle mirror assembly; and

FIG. 10 is a schematic view of an alternate embodiment of the lightreceiving components of the vehicle mirror assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

Referring to FIG. 1, a vehicle mirror assembly 10 comprises a reflectiveelement 21 for reflecting incident light, a means for varying theintensity of light reflected from the reflective element in the form ofan electro-optic dimming element 20 and an external glass pane 12. Thedimming element 20 takes a number of forms. For instance the dimmingelement 200 is in the form of a gel or liquid containing crystals orother suspended particles (such as used in LCD displays orelectro-chromic films). Any other suitable electro-optic device may beused.

The reflective element 21 is selected to reflect approximately 60% ofincident light. A portion of the remaining 40% of the light passesthrough the reflective element 21 and through an internal glass pane 22to a device for converting light into electrical power that is aphoto-electrical power cell, in the form of a photo-voltaic cell 35. Thephoto-voltaic cell 35 is provided to power the dimming element 20. Aphoto-electrical switching device in the form of a photo switch 36 isconnected to the photo-voltaic cell 35 and is connected to an electrode27 through a conductor 27′. This electrode 27 is either a separateelement or the reflective element functioning as an electrode. A secondelectrode 26, that is transparent, is connected to the photo-voltaiccell 35 by a conductor 26′ as shown in FIG. 1.

The photo switch 36 (or alternatively another photo-electrical switchingdevice such as a light sensitive resisting element) in combination witha directional filter 32 provides a means for controlling the dimmingelement 20 in response to the ambient light conditions.

With the embodiment shown in FIG. 1, the photo switch 36 is connected inseries with the power source 35 and therefore is designed to switch off,or substantially off, when it receives strong ambient light, therebyensuring that power from the power source 35 does not flow to thedimming element during day light hours (or other times of high ambientlight).

In other embodiments, not shown, photo switches 35 that switch on whenthey receive light are employed in conjunction with an alternativeappropriate circuit arrangement.

Directional filters 30 and 32 are provided between the internal glasspane 22 and the photo-voltaic element 35 and the photo switch 36respectively to insure that only incident light from selected directionsreach the photovoltaic element 35 and photo switch 36, respectively.

As shown in FIG. 1, the glare directional filter 30 is arranged to allowincident light “I” with incident angle e+/−b (measured with respect tothe plane of the reflective element 21) to reach the photo-voltaicelement 35. Light having an incident angle outside this range, isprevented from reaching the photo-voltaic element 35 by the directionalfilter 30. Because the photo-voltaic element 35 powers the dimmingelement 20, power is only available from light with an incident anglethat will pass through the glare filter 30. In other words, the dimmingelement 20 only receives power from glare light and therefore only dimsglare light. Depending on the application, the incident angle of glarelight allowed through by the dimming element 20 may be varied.

For a driver's side mirror, directional filter 30 is orientated at about76° (angle e shown in FIG. 1) to the plane of the reflective element 21.(For a passenger side mirror, directional filter 30 is orientated atabout 60°). The directional filter 30 is constructed so as to allowlight having an incident angle e=76° (60°)+ or −b=20° to allow formirror angle adjustment for different drivers.

In high ambient light conditions, it is not necessary or desirable tohave the dimming element 20 operational. An ambient light directionalfilter 32 is provided between the internal glass 20 and the photo switch36 to ensure that ambient light “A” coming from directions outside ofthe glare directions reaches the photo switch 36. In this embodiment,the directional filter 32 allows light to pass through where that lighthas an incident angle of c+/−g (to the plane of the reflective element21). With this arrangement, during periods of high ambient light (suchas during daylight hours) light reaches the photo-switch 36 causing areduction (or elimination) of signals to the dimming element 20. Thereduced (or eliminated) signals result in little or no dimming of thedimming element 20. Thus in daylight conditions, the mirror functionslike a conventional non-dimming mirror.

The angles shown in FIG. 1 and discussed above are all measured with ahorizontal plane parallel to the ground. However, in an alternateembodiment, the ambient light directional filter 32 is orientated todiscriminate against light from this plane, thereby, avoiding glarelight interference. In another alternate embodiment, the ambient lightdirectional filter 32 is crescent shaped and is positioned at anyconvenient location around the mirror.

FIG. 2 shows an alternative embodiment of a first preferred form of theinvention in which a vehicle mirror assembly 10 comprises a reflectiveelement 21, a means for varying the intensity of light reflected fromthe reflective element in the form of an electro-optic dimming element20 and an external glass pane 12. With this embodiment of the invention,a light concentrator in the form of a fresnel lens 24 is used inconjunction with a photo-voltaic cell 35. By using such a concentratorthe intensity of the light falling on the photo-voltaic cell 35 isincreased and the need for a directional filter, such as directionalfilter 30 shown in FIG. 1, is eliminated. (A fresnel lens is inherentlydirectional).

FIG. 3 shows a further alternative embodiment of a first preferred formon the invention. With this embodiment, the reflective element 21 andthe dimming element 20 are one. The reflective element 21 is anelectro-optic device capable of changing its level of reflectance inresponse to the application of a voltage. Various electro-optic devicesare used to provide such a variable reflective element.

With both of the above two embodiments shown in FIGS. 2 and 3, thecontrol means for controlling the level of reflectivity of thereflecting element 21 take a number of forms. For instance it takes theform of a combination of a directional filter and a photo switch, suchas that used in the embodiment described and illustrated in FIG. 1, orit takes the form of a controller described below.

The photo-voltaic cell 35 is positioned behind the reflective element 21in all the abovedescribed embodiments (shown in FIGS. 1, 2, and 3). Inan alternate configuration, a transparent photoelectric power cell (aphoto-voltaic cell or a solar cell) 35 is placed in front of (on theviewable side) of the reflective element 21.

With the embodiment shown in FIG. 1 a, the power to the dimming element20 is reduced when incident light is non glare light since the projectedarea of the solar cell 35 is reduced where the angle of incidence of thelight is high. In addition to this effect, a transparent solar cell 35having directional properties is employed. In this way, the overallassembly will not dim the image reflected to the driver excessively whennon glare light is incident on the mirror.

With the embodiment shown in FIG. 1 b, a further photo switch 37together with a directional filter 31 is employed. These additionalelements are provided to ensure that only glare light activates thedimming element 20. With this arrangement, a solar cell 35 with noinherent directional properties or poor inherent directional propertiesis employed.

An embodiment of a second preferable form of the invention,diagrammatically illustrated in FIG. 4, is similar to the embodiment ofthe first preferable form of the invention described above but ambientlight, rather than glare light, is used as a power source. With thisembodiment, a power storage means such as a rechargeable battery 42 isused to store power generated by a photo-voltaic cell (in the form of asolar cell 35) from ambient light (such as sun light). This stored poweris used to power the dimming element 20 when glare light is incident onthe mirror.

This embodiment also shows an alternative to the use of directionalfilters to control the level of reflective light. In this embodiment, acontroller 40 is employed. The controller 40 receives signals from aforward facing photo-electric cell 50 and a rearward facingphotoelectric cell 52. The forward facing cell 50 detects ambient lightand the rearward facing cell 52 detects glare light.

With each of the above described embodiments the reflective element 35is selected so as to allow some transmission of light through aphoto-voltaic element and/or a photo-switch or resisting element, forinstance a reflective element 21 having 60% reflectance and up to 40%transmission is used.

The signal to the dimming element 20 is voltage, current, or pulse widthmodulated signal controlled by the light levels. For example, conductor27′ in FIG. 1 is replaced by controller 40 for appropriate signalprocessing.

A slow change in the level of dimming is desirable to prevent a problemwith extraneous light sources (e.g. street lights etc). This is achievedby the use of smoothing electronics where the response time of thedimming element 20 is too high.

With the embodiments illustrated in FIGS. 1 to 3 described above, thelight powering the dimming element 20 must first pass through thereflective element 21. As stated above in one embodiment, the reflectingelement 21 only transmits 40% or less of the incident light (with theremainder being reflected or absorbed). FIGS. 5, 6, and 7 showalternative configurations in which the light receiving aperture or lensfor at least the photo-voltaic element 35 (and desirably the photoswitch 36) is not located behind the reflective element 21. With theseconfigurations, a light receiving module 38 is positioned adjacent themirror in either the base 14 (as shown in FIG. 5), the leg 15 (as shownin FIG. 6), or around the periphery of the mirror in a housing 16 (asshown in FIG. 7). These configurations allow capture of more lightenergy per unit area.

FIGS. 8 to 10 show schematically three alternative arrangements for thelight receiving apertures or lenses for the photo-voltaic cell 35 andthe photo switch 36.

FIG. 8 shows two concentrator lenses 24 and 25 (a convex lens or afresnel lens) for concentrating light energy onto photo-voltaic element35 and photo switch 36 respectively. Lens 25 is angled such that ambientlight is received, but glare light is not received by photo switch 36.

FIGS. 9 and 10 each show two directional filters 30 and 32 for passinglight energy onto photo-voltaic element 35 and photo switch 36,respectively.

All of the above described embodiments of the invention are powered bysources of light. Therefore, no power is required from the vehicle towhich the dimming mirror (or mirrors) is mounted. In some applications,this can greatly simplify both the design integration of the mirror inthe vehicle and assembly of the mirror to the vehicle.

With the above-described embodiments glass sheets are used. In someapplications it is preferable to use plastic. The term “glass” shall betaken to include transparent plastic.

International Application No. PCT/AU02/00352 titled “Vehicle externalmirror wiring integration” discloses a pivot assembly having contactsmounted on detent surfaces for transmission of power from the base tothe head. These features and other features disclosed in PCT/AU02/00352could be used with the present invention and the disclosure ofPCT/AU02/00352 is herewith incorporated in its entirety into thisspecification.

International Application No. PCT/AU02/00353 titled “External vehiclemirror having self-loading pivot and improved end stop” discloses amirror assembly having a self-loading pivot mechanism wherein initialrotation of the mirror head with respect to the mirror base causespre-loading of a spring. These features and other features disclosedcould be used with the present invention and the disclosure ofPCT/AU02/00353 is herewith incorporated in its entirety into thisspecification.

International Application No. PCT/AU00/00413 titled “Method of producinga plastic moulded part including a film covering” discloses a method offorming a moulding component comprising an outer thin film componentwith an adhered moulded shell. The method of that disclosure could beused to mould hollow form components that may be used with thisinvention (for instance for the shell of the head and base) and thedisclosure of this application is incorporated herewith in its entirety.

Australian provisional patent application PR6683 titled “Foldablevehicle external mirror having auxiliary mirror” discloses a vehicleexternal mirror having an auxiliary mirror mounted to a distal side ofthe mirror head. The auxiliary mirror provides rear vision when themirror head is in its folded position. This feature and other featuresdisclosed in PR6683 are/could be used with the present invention.Specifically, for this instance, an auxiliary or “spotter” mirror may beused in association with a dimmable main mirror. The auxiliary mirrormay be a plain mirror or may itself be dimmable. The disclosure ofPR6683 is herewith incorporated in its entirety into this specification.

Australian provisional patent application number PR6204 titled “MirrorHeater” discloses an automatic heating control system and apparatus forheating the surface of a mirror to de-ice or de-fog the mirror. Theheating process is initiated upon starting the vehicle engine, and isconducted in accordance with a pre-set timing sequence and in accordancewith an actual measured temperature of the mirror. These features andother features disclosed in this document could be used with the presentinvention and the disclosure of PR6204 is hereby incorporated in itsentirety into this current specification.

It would also be possible to incorporate other components with themirror base (mounting bracket) and or mirror head. Such componentsinclude electronic sensors such as proximity sensors to determine if thevehicle mirror is close to an obstruction, sensors that sense externaltemperature and humidity, and sensors incorporated with the car securitysystem such as motion detectors. Other various electronic equipment maybe incorporated into the mirror base (mounting bracket) such as lightsused to light the area around the vehicle, or lights that may becontrolled from within the vehicle that enable the light to be moved soas to provide directional lighting. Speakers and microphones used tocommunicate to people external of the vehicle may also be incorporatedas well as antennas for various apparatus such as mobile phones, GPSdevices and other radio communication devices. In addition, transmittersmay be incorporated into the mounting bracket which are used forcontrolling external objects such as garage doors or providing radiotransmissions which may be used, for example, to track or locate thevehicle. Other electronic devices such as automatic toll payment systemsor remote transaction systems may be incorporated into the mountingbracket to enable electronic registration of various toll payments.

Cameras may also be incorporated into the mirror base (mounting bracket)which are both forward and rearward looking which are designed tocontinuously record digital images and to store those images either oncommand or as a result of an accident or incident. Motion sensorsincluding accelerometers can be used to determine the occurrence of anaccident or incident so that images before and after the event arestored.

While the present invention has been described in terms of preferredembodiments in order to facilitate a better understanding of theinvention, it should be appreciated that various modifications can bemade without departing from the principles of the invention. Therefore,the invention should be understood to include all such modificationswithin its scope.

1. A vehicle mirror assembly comprising: a reflective element forreflecting incident light, the reflective element having a viewableside; a dimming element for varying the intensity of incident lightreflected from the viewable side; a photo-electrical power cell forpowering the dimming element; a controller for controlling the dimmingelement; a first directional element for allowing incident light havingan angle of incidence falling within a first preset range with respectto the reflective element to reach the photo-electrical power cell, andfor preventing incident light having an angle of incidence fallingoutside the first preset range from reaching the photo-electrical powercell; a photo-electrical switching device; and a second directionalelement for allowing ambient light having an angle of incidence fallingwithin a second preset range with respect to the reflective element toreach the photo-electrical switching device, wherein power is suppliedfrom the photo-electrical power cell to the dimming element as a resultof incident light reaching the photo-electrical power cell, and whereinthe power supplied from the photo-electrical power cell to the dimmingelement is reduced as a result of ambient light reaching thephoto-electrical switching device.
 2. A vehicle mirror assembly asclaimed in claim 1 wherein the photo-electrical power cell is adapted toutilize the incident light from a vehicle's headlight to producesufficient real-time power for the dimming element.
 3. A vehicle mirrorassembly as claimed in claim 2 wherein the dimming element comprises anelectrically dimmable light transmitting sheet or panel, the sheet orpanel overlaying the viewable side of the reflective element.
 4. Avehicle mirror assembly as claimed in claim 3 wherein the electricallydimmable light transmitting sheet or panel comprises a gel or liquidcontaining suspended particles or crystals.
 5. A vehicle mirror assemblyas claimed in claim 2 wherein the dimming element includes thereflective element, the reflectiveness of the reflective element beingelectrically variable.
 6. A vehicle mirror assembly as claimed in claim1 wherein the first directional element comprises a directional filter.7. A vehicle mirror assembly as claimed in claim 1 wherein the firstdirectional element comprises a Fresnel lens.
 8. A vehicle mirrorassembly as claimed in claim 1 wherein the second directional elementcomprises an ambient light directional filter.
 9. A vehicle mirrorassembly as claimed in claim 1 wherein the first preset range is 76degrees ±20 degrees.
 10. A vehicle mirror assembly as claimed in claim 1wherein the first preset range is 60 degrees ±20 degrees.
 11. A vehiclemirror assembly comprising: a reflective element for reflecting incidentlight, the reflective element having a viewable side; a dimming elementfor varying the intensity of light reflected from the viewable side ofthe reflective element, wherein the dimming element overlays theviewable side of the reflective element; a transparent photo-electricalpower cell overlaying the dimming element for powering the dimmingelement; a controller for controlling the dimming element; a firstphoto-electrical switching device; a first directional element forallowing ambient light having an angle of incidence falling within afirst preset range with respect to the reflective element to reach thefirst photo-electrical switching device, and for preventing ambientlight having an angle of incidence falling outside the first presetrange with respect to the reflective element to reach the firstphoto-electrical switching device; a second photo-electrical switchingdevice; a second directional element for allowing incident light havingan angle of incidence falling within a second preset range with respectto the reflective element to reach the second photo-electrical switchingdevice; wherein power is supplied from the transparent photo-electricalpower cell to the dimming element as a result of the incident lightreaching the second photo electrical switching device; and wherein thepower supplied from the transparent photo-electrical power cell to thedimming element is reduced as a result of ambient light reaching thefirst photo-electrical switching device.
 12. A vehicle mirror assemblyas claimed in claim 11 wherein the photo-electrical power cell isadapted to utilize the incident light from a vehicle's headlight toproduce sufficient real-time power for the dimming element.
 13. Avehicle mirror assembly as claimed in claim 12 wherein the dimmingelement has an electrically dimmable light transmitting sheet or panel,the sheet or panel overlaying the viewable side of the reflectiveelement.
 14. A vehicle mirror assembly as claimed in claim 13 whereinthe electrically dimmable light transmitting sheet or panel has a gel orliquid containing suspended particles or crystals.
 15. A vehicle mirrorassembly as claimed in claim 12 wherein the dimming element has thereflective element, the reflectiveness of the reflective element beingelectrically variable.